Messages in this thread Patch in this message | | | Date | Sat, 21 Mar 2020 15:53:53 -0000 | From | "tip-bot2 for Logan Gunthorpe" <> | Subject | [tip: locking/core] PCI/switchtec: Fix init_completion race condition with poll_wait() |
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The following commit has been merged into the locking/core branch of tip:
Commit-ID: efbdc769601f4d50018bf7ca50fc9f7c67392ece Gitweb: https://git.kernel.org/tip/efbdc769601f4d50018bf7ca50fc9f7c67392ece Author: Logan Gunthorpe <logang@deltatee.com> AuthorDate: Sat, 21 Mar 2020 12:25:45 +01:00 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Sat, 21 Mar 2020 16:00:20 +01:00
PCI/switchtec: Fix init_completion race condition with poll_wait()
The call to init_completion() in mrpc_queue_cmd() can theoretically race with the call to poll_wait() in switchtec_dev_poll().
poll() write() switchtec_dev_poll() switchtec_dev_write() poll_wait(&s->comp.wait); mrpc_queue_cmd() init_completion(&s->comp) init_waitqueue_head(&s->comp.wait)
To my knowledge, no one has hit this bug.
Fix this by using reinit_completion() instead of init_completion() in mrpc_queue_cmd().
Fixes: 080b47def5e5 ("MicroSemi Switchtec management interface driver")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lkml.kernel.org/r/20200313183608.2646-1-logang@deltatee.com --- drivers/pci/switch/switchtec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c index a823b4b..81dc7ac 100644 --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -175,7 +175,7 @@ static int mrpc_queue_cmd(struct switchtec_user *stuser) kref_get(&stuser->kref); stuser->read_len = sizeof(stuser->data); stuser_set_state(stuser, MRPC_QUEUED); - init_completion(&stuser->comp); + reinit_completion(&stuser->comp); list_add_tail(&stuser->list, &stdev->mrpc_queue); mrpc_cmd_submit(stdev);
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